The solvents hitherto proposed and used for pharmaceutical preparations are not entirely satisfactory in view of their various properties, for example the dissolving power, the miscibility with other solvents and especially the physiological compatibility. The disadvantages of such commercial pharmaceutical solvents are described, for example, in German Auslegeschrift No. 2 708 419. In said Auslegeschrift there are described the advantageous properties of 1,2-butanediol 1-methyl ether as the solvent for pharmaceutical purposes. It has, meanwhile, been established that this compound produces changes in the blood.